Liquid chromatographic method for monitoring therapeutic concentrations of L-dopa and dopamine in serum.

Abstract

We describe a new method for the simultaneous assay of 3,4-dihydroxyphenylalanine (L-dopa) and dopamine in serum. Both compounds have been determined quantitatively at concentrations as low as 10 mug/liter with a coefficient of variation of less than 4%. Peak heights were linearly related to concentration up to 10 mg/liter for each compound. Assay of human sera gave within-run and day-to-day coefficients of variation of 2.8% and 3.1% for L-dopa, and 2.9% and 3.7% for dopamine. The linear relationship between readings nA, y-axis) and concentration (mug/liter) is described by the following equations: y = (21.0 +/- 0.082)x + (0.46 +/- 0.31 SD) for L-dopa and y = (17.0 +/- 0.10)x + (0.08 +/- 0.04 SD) for dopamine. The procedure combines liquid/solid extraction, liquid chromatography, and controlled-potential electrochemistry. The simplicity, sensitivity, and accuracy of this method make it suitable for routine clinical analysis of serum samples to optimize bioavailability for individual patients. After the extraction procedure is completed, samples can be analyzed at the rate of 10/h.

Label-Free Graphene Oxide Förster Resonance Energy Transfer Sensors for Selective Detection of Dopamine in Human Serums and Cells

“…As shown in Figure b, an excellent linear relationship between the relative fluorescence enhancement and the DA concentration in serum within the range from 1.44 to 11.48 μmol L –1 was observed, which can be fitted to the equation: ( I – I 0 )/ I 0 = 1.068 log C DA – 2.010 ( R 2 = 0.9900). It has been previously reported that the lowest concentration of DA in serum is approximately 1.0–1.5 μmol L –1 . Therefore, our DOX–GO sensor can be fine-tuned to detect DA in serum with a good sensitivity.…”

“…It has been previously reported that the lowest concentration of DA in serum is approximately 1.0−1.5 μmol L −1 . 33 Therefore, our DOX−GO sensor can be fine-tuned to detect DA in serum with a good sensitivity. We further tested the newly developed DOX−GO sensors in cells.…”

“Negative electrocatalysis”-based specific analysis of dopamine at basal plane HOPG in the presence of structurally related catecholamines

“…Thus, a more pronounced "negative electrocatalysis" [12] observed for norepinephrine (very similar data for epinephrine were obtained) and catechol oxidations on HOPG as compared to dopamine allowed discrimination between dopamine and those catecholamine oxidation signals ( Figure 4A). It was used for specific analysis of dopamine in CSF at its concentrations corresponding to in vivo conditions (within the 10 nM (basal levels) to 4-6 µM range) [20,21], in the presence of norepinephrine, epinephrine, catechol and ascorbic acid (on GC those processes overlapped).…”

Integration of ring nanoelectrodes into microwells for the bioelectrochemical analysis in sub-picolitre volumes

“…. As a matter of fact, it should be concluded that the DME-RNE system can address electroanalytical selectivity problems but is not adapted to the detection of dopamine in presence of ascorbic acid in the frame of blood analysis ([AA]/[Dop] > 10[46,47]). 4.…”